The construction of a p-n heterojunction is an efficient strategy to resolve the limited light absorption and serious charge-carrier recombination in semiconductors and enhance the photocatalytic activity. However, the promotion effect is greatly limited by poor interfacial charge transfer efficiency as well as reduced redox ability of charge carriers. In this work, we demonstrate that the embedding of metal Pd into the interface between n-type C3N4 and p-type Cu2O can further enhance the interfacial charge transfer and increase the redox ability of charge carriers through the design of the C3N4-Pd-Cu2O stack nanostructure. The embedded Pd nanocubes in the stack structure not only trap the charge carriers from the semiconductors in promoting the electron-hole separation but also act as a Z-scheme "bridge" in keeping the strong reduction/oxidation ability of the electrons/holes for surface reactions. Furthermore, Pd nanocubes also increase the bonding strength between the two semiconductors. Enabled by this unique design, the hydrogen evolution achieved is dramatically higher than that of its counterpart C3N4-Cu2O structure without Pd embedding. The apparent quantum efficiency (AQE) is 0.9% at 420 nm for the designed C3N4-Pd-Cu2O. This work highlights the rational interfacial design of heterojunctions for enhanced photocatalytic performance.

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(730) high index faceted PtCu concave nanocube cocatalysts were designed for enhanced photocatalytic performance of C3N4–PtCu hybrid structures in the reduction of CO2 to CH4.

Constructing a step-scheme (S-scheme) heterojunction represents a promising route to overcome the drawbacks of single-component and traditional heterostructured photocatalysts by simultaneously broadening the optical response range and optimizing the redox ability of the photocatalytic system, the efficiency of which greatly lies in the separation behaviors of photogenerated charge carriers with strong redox capabilities. Herein, we demonstrate interfacial facet engineering as an effective strategy to manipulate the charge transfer and separation for substantially improving the photocatalytic activities of S-scheme heterojunctions. The facet engineering is performed with the growth of ZnIn 2 S 4 on ( 010) and (001) facet-dominated BiOBr nanosheets to fabricate ZIS/BOB-(010) and ZIS/BOB-(001) S-scheme heterojunctions, respectively. It is disclosed that a larger Fermi level difference between BiOBr-(001) and ZnIn 2 S 4 enables the formation of a stronger built-in electric field with more serious band bending in the space charge region around the interface. As a result, the directional migration and recombination of pointless photoexcited electrons in the conduction band (CB) of BiOBr and holes in the valence band (VB) of ZnIn 2 S 4 with weak redox ability are speeded up enormously, thereby contributing to more efficient spatial separation of powerful CB electrons of ZnIn 2 S 4 and VB holes of BiOBr for participating in overall redox reactions. Profiting from these merits, the ZIS/BOB-(001) displays a significant superiority in photocatalytic H 2 evolution over ZIS/BOB-(010) and mono-component counterparts. This work provides new deep insights into the rational construction of a S-scheme photocatalyst based on an interfacial facet design from the viewpoint of internal electric field regulation.